A known type of seal or gasket, introduced among others by document WO-A1-2012095601, comprises a longitudinal elastomer section inserted in a groove provided in a support plane of a part, that is compressed at the same time at the bottom of this groove, and on an additional flat surface of a second part clamped on this first support plane, so as to ensure an imperviousness between these two parts.
This type of seal or gasket is used among others to ensure the imperviousness in a combustion engine, in particular for clamping a cylinder head cover on this cylinder head. It can be achieved with various elastomer types that can be compressed, such as rubber or synthetic polymers.
The cross-section of the gasket or seal comprises a certain height that ensures at any point a sufficient compression of this gasket, guaranteeing imperviousness continuously on the corresponding flat surface.
The gasket can include according to the location specific shapes added to the section, to produce for instance the circumventing of securing screws, the imperviousness in a non-flat area comprising a shaft bearing or the assembly of three parts among each other.
In particular, the section comprises at least one part of its cross-section that presents lengthwise a continuously variable geometry, in order to reduce the quantity of material used, and to decrease cost. This variable geometry may present a wave.
The section can also include on each side of the cross-section, in a central part, a low-height side boss and of constant section that extends longitudinally, taking support on the sides of the groove so as to produce a lateral blocking of the gasket or joint to avoid its tilting when it is compressed between the two parts.
However, tests have indicated that for mass production comprising dispersions of dimensions, this type of seal or gasket might cause problems of lateral tipping of its section, or of pinching between the two support faces when they are clamped one against the other.
Among other, the purpose of this invention is to prevent these drawbacks of the prior state of the art.
For that purpose, it proposes an elastomer seal or gasket to be inserted in a groove vertically on a support plane of a part, and clamped or tightened against an additional flat surface, with this seal or gasket showing at least a portion of its cross-section comprising longitudinally a continuously variable shape, characterized in that it includes spaced on at least one side, fine side strips arranged vertically.
An advantage of this seal or gasket is that the side strips constitute by virtue of their height lateral supports on the sides of the groove that prevent this seal or gasket from tipping during its mounting and clamping or tightening.
This way, simply and economically through additional shapes made to the molding and by adding a small amount of material, a stability of the seal is achieved which in spite of the dispersions of the dimensions of the section of the groove or seal, guarantees in all cases a proper assembly and a good imperviousness.
The seal or gasket according to the disclosure may also include one or several of the following features which can be combined with each other.
In particular, the side strips may include a curved profile turned to the outside. This curved profile facilitates a crushing of the material.
Beneficially, the side strips reach in height below the top surface of the seal or gasket. This way one avoids having at the seal plane level during vertical compression of the impervious seal, support material on the side of the groove that might be pinched during clamping or tightening of the parts to be assembled.
In particular, the side strips may extend over about two thirds of the height of this seal or gasket, centered over this height.
According to a method of embodiment of this disclosure, the seal or gasket comprising top and bottom parts of its cross-section which are continuously variable, the side strips cover about half of these top and bottom parts.
Beneficially, the seal or gasket comprises side strips which on either side of this seal, are longitudinally offset alternatively. As such, a regularly distributed lateral stability over the length of the seal or gasket is ensured.
In particular, the continuously variable shape may constitute a sinusoid.
In this case, beneficially, the seal or gasket comprises a side strip on each side, at each top of the sinusoid.
According to a method of embodiment of the disclosure, the seal or gasket comprising a central part of its cross-section showing longitudinally a constant section, this central part comprises on each side a longitudinal rib that extends towards the outside.
Beneficially, the side strips exceed the longitudinal rib transversally.
The purpose of the disclosure is also a set of two parts assembled to each other by an impervious flat surface with each of these parts comprising a groove containing a seal or gasket that comprises any of the preceding features.
In particular, one of the parts of this unit may constitute a cylinder head of a combustion engine, with the other part forming a cover for said cylinder head.